1591236505081 has 2 divisors, whose sum is σ = 1591236505082. Its totient is φ = 1591236505080.

The previous prime is 1591236505051. The next prime is 1591236505139. The reversal of 1591236505081 is 1805056321951.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1591117346025 + 119159056 = 1261395^2 + 10916^2 .

It is an emirp because it is prime and its reverse (1805056321951) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1591236505081 - 2⁷ = 1591236504953 is a prime.

It is a super-2 number, since 2×1591236505081² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1591236505051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 795618252540 + 795618252541.

It is an arithmetic number, because the mean of its divisors is an integer number (795618252541).

Almost surely, 2^{1591236505081} is an apocalyptic number.

It is an amenable number.

1591236505081 is a deficient number, since it is larger than the sum of its proper divisors (1).

1591236505081 is an equidigital number, since it uses as much as digits as its factorization.

1591236505081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 324000, while the sum is 46.

The spelling of 1591236505081 in words is "one trillion, five hundred ninety-one billion, two hundred thirty-six million, five hundred five thousand, eighty-one".